If you're using HyperRESEARCH on an OS X system, and you have recently upgraded to OS X 10.6 "Snow Leopard", you may experience a problem when opening a study file. Specifically, if your study file does not have the extension ".hs2" at the end of the file name, and you double-click your study file in order to open it, you may see an error message indicating that the file type is "unsupported".
To successfully open the file, first start up HyperRESEARCH, then choose the "Open Other Study" option in the startup dialog box (or choose File > Open Study). Locate your study file in the Open File dialog box, and it will open normally. Once you do this, the file appears in the Recent Studies popup menu, so you can easily open it when starting up HyperRESEARCH.
(The reason this happens is that Apple made a minor change in Snow Leopard to the way file identifications are handled.)